When a person, usually a guy, is prone to crying about things such as girls who don't like them, projects that don't work, shoes that are falling apart, bikes that get stolen and the fact that they want to go back to Mexico. It is a trait that is predominant in guys named Dan.
Also: a genre of music popular amongst Long Island high school students in the late 1990s/early 2000s.
"Dan is so emo. All he does is whine about how hard it is to talk to girls."
"Ugh. Don't you know that emo hasn't been cool since 2004."
"Dan is so emo. He busted a hole in his new Adidas sneakers, and started to cry."